1. Field of the Invention
The present invention relates to keyboards and more particularly, to keyboards having keys for use with digital computer systems such as, for example, mail sorting computer keyboards.
2. Art Background
Prior art keyboards used in conjunction with mail sorting equipment typically have various adjustment mechanisms for determining the maximum downward and upward movement of the keys. After extended use of the keyboard, such adjustment mechanisms frequently go out of alignment, such that the keyboard does not function in its intended manner, thereby requiring readjustment of the adjustment mechanisms. The afore-stated problem of prior art keyboards is particularly critical in mail sorting keyboards which are used by the United States Postal Service in conjunction with mail sorting machines.
In FIG. 2 there is shown a perspective interior view of a lower portion of a typical prior art mail sorting keyboard generally denoted by reference numeral 9. The prior art mail sorting keyboard 9 has two lateral portions 9A and 9B which are disposed at each longitudinal end of the keyboard 9, and which are separated by a gap 53. Keyboard portion 9B mirrors, but is otherwise identical to keyboard portion 9A, and, therefore, a description of keyboard portion 9A will fully convey to the reader an appreciation of the problems and drawbacks associated with such prior art keyboards.
Keyboard portion 9A of FIG. 2 is comprised of a plurality of keys 7 which are longitudinally aligned with one another, each key of the plurality of keys 7 is comprised of a plastic portion 7A which is disposed over and attached to a pair of supporting arms 7B. The supporting arms 7B each join a transverse portion 7C which is disposed across arms 7B at the region thereof underlying plastic portions 7A, as shown in FIG. 2. Each pair of supporting arms 7B has disposed at the ends thereof opposite the plastic portion 7A of the keys 7 recesses 51 and 52 through which is disposed an elongate rod 6 which has a circular cross section uniformly along its length such that together, recesses 51 and 52 and elongate rod 6 provide a pivot means for each of the keys 7. Disposed generally underneath each pair of supporting arms 7B is an electrical switch 8 which is interfaced with a mail sorting keyboard system (not shown). Disposed above each electrical switch 8 is an alignment means 11 which is comprised of a transverse plate portion 11A, a threaded collar portion 11B and a threaded bolt 11C which has a flanged bottom portion 11D. The transverse plate portion 11A is coupled to each upper edge of supporting arms 7B, as shown in FIG. 2, and is unitary therewith. Disposed generally in the center of transverse plate portion 11A is the threaded collar portion 11B. Threaded through threaded collar portion 11B is the threaded bolt 11C which has the bottom flanged portion 11D. Disposed underneath the flanged portion 11D of the threaded bolt 11C there is disposed a pressure actuated switch portion (not shown) which comprises a part of each electrical switch 8. When a key is depressed, the flanged portion 11D of the bolt 11C comes into contact with and depresses the pressure actuated switch portion of a corresponding switch 8 thereby closing electrical switch 8 and initiating a predetermined pulse to the mail sorting keyboard system.
Threaded bolt portion 11C has a central opening into which may be inserted an allenhead wrench for threading the bolt through threaded collar portion 11B in an upwards or downwards direction. It will be appreciated that after constant use, each threaded bolt 11C will thread upwards or downwards thereby increasing or decreasing the distance between the flanged portion 11D and the pressure actuated switch portion of the switch 8. As such, the pressure actuated switch portion of each switch 8 will then be improperly actuated. At such time, each threaded bolt 11C must be adjusted such that the distance between the flanged portion 11D is properly set so that the pressure actuated switch portion of switch 8 is properly actuated when a corresponding key is depressed.
Also disposed transversely across and above the plurality of keys 7 is a second alignment means 13 which is similar to alignment means 11, and which comprises a transverse channel 13A disposed transversely across the keyboard 9 adjacent to the end of plastic portions 7A. As shown in FIG. 2, disposed along the transverse channel 13A is a plurality of threaded collar portions 13B, each of which is disposed above each key of the plurality of keys 7. Disposed within each threaded collar portion of alignment means 13 is a plurality of threaded bolts 13C each having a bottom flanged portion (not shown), which are also disposed above each transverse portion 7C of each key of the plurality of keys 7. Each bolt 13C is threadedly engaged with a corresponding threaded collar portion 13B. Disposed under each key of the keys 7 is a spring (not shown) which upwardly biases each key. As such, each flanged portion of each bolt, when a key is not depressed by a user, abuts against a felt member portion 13E thereby determing the extent of upward movement of each key of the plurality of keys 20. It will be appreciated that over periods of constant use, the bolt 13C may turn upwards or downwards within threaded collar 13D, thereby increasing or decreasing the extent of upward or downward movement of the corresponding key of the plurality of keys 7 thereby also causing the key to go out of alignment, and necessitating realignment by turning the bolt 13B in the same manner as previously discussed with respect to bolt 11C of alignment means 11.
It will be further appreciated that since each key of keyboard portion 9A has two alignment means, 11 and 13, each of which comprises five separate portions, the plurality of keys 7 have, collectively, ten separate alignment mechanisms each of which must be periodically adjusted over the course of the operation of the keyboard portion 9A. Taking into account keyboard portion 9B, it will be appreciated that keyboard 9 periodically requires twenty individual adjustments in order to keep the keys properly aligned. Such periodic and multiple adjustments result in downtime of the keyboard 9 thereby incurring great cost. Moreover, in situations wherein the adjustment means 11 and 13 are out of alignment and the keyboard 9 is operated, the pressure actuated switch portions of switches 8 are often not actuated when a corresponding key is depressed such that, electronic pulses are not properly conveyed to the mail sorting keyboard system thereby causing inputting errors, and resulting in an improper classification of the mail being sorted. Additionally, since the prior art mail sorting keyboard 9 is comprised of many intricate parts, manufacture and assembly of the same is costly and a complicated procedure.